Lifting jack



C. H. JOHNSON LIFTING JACK April 18, 1950 Filed July 28, 1945 INVENTOR. CLAUDE H.JOHNSON J ATTORNEY Patented Apr. 18, 1950 OFFICE LIFTING JACK Claude H. Johnson, Pontiac, Mich. Application July 28, 1945, Serial No. 607,588

This invention relates to lifting jacks and particularly vehicle lifting jacks.

Among the broader objects of the invention are to provide a screw type jack of superior simplicity with a consequent low manufacturing cost, and to adapt a vehicle jack to be readily disassembled and very compactly stored, when not in use.

More specific objects are to apply the lifting thrust of a jack screw to an upright bar, whereon said screw issuperposed, to employ said bar as a guide for a load-transmitting slide supported by a nut engaging the screw, and to adapt a load-engaging adapter to be attached at selective levels to said slide in a simple and novel manner.

In the prior art it has been proposed to seat a rotative jack screw directly on the jack base, but such an arrangement does not lend itself to a compact disassembly, entails use of a heavier screw than is required by my construction, and imposes a binding effect on the nut engaging said screw.

It has also been proposed heretofore to extend a hollow column upwardly from a jack base, to journal a screw on the upper end of such column and extend it downwardly in the column to raise or lower a nut guided within the column. This involves complexity in transmitting a load to the housed-in nut, which complexity is costly.

The objects aforementioned and various other objects are attained by the construction hereinafter described and illustrated in the accompanying drawing, wherein:

Fig. l is a view of the improved jack in sectional elevation.

Fig. 2 is a top plan view of the jack.

Fig. 3 is a front view of the jack.

Fig. 4 is a perspective view of the load-engaging adapter.

In these views, the reference character I designates a base which may be inexpensively formed as a sheet metal stamping, its center portion being of a dome form and having a shallow socket 2 of spherical contour. Seated on said base in the socket 2 is an upstanding cylindrical thrust bar 3 having a shallow socket 4 in its upper end. superposed on the bar 3 and rotatively seated in the socket 4 is a screw 5 of lesser diameter than the bar 3. Rotation of the screw is adapted to raise or lower a nut 6 which is safeguarded against excessive tilting stresses by a tubular slide 1 whose upper end snugly houses the nut and whose lower portion slidably fits the bar 3.

3 Claims. (01. 254-98 The nut and slide are rigidly interconnected,

preferably by welding. The slide 1 carries a load engaging adapter 8 and it is preferred to rigidly equip the slide with a channel-shaped support 9 for the adapter, such support being preferably coextensive in length with the slide and welded at its edges to the latter. Thus said support has a face radially spaced from the slide, and the adapter 8 is engageable with such face, being formed with spaced upper and lower pins [0 and H engageable in perforations 12 a row of which extends substantially from end to end of the support 9. The adapter is formed preferably of heavy sheet metal having a downwardly extending notch l3 to accommodate a vehicle bumper or the like. The upper pin I0 is upwardly hooked so that it may resist the turning moment imposed by a load acting about the lower pin II as a fulcrum. Any suitable provision may be made for manually rotating the screw, there being shown a slip handle I transversely extending through the upper end of the screw.

In use of said jack, the adapter 8 is first disposed at such a level on the support 9 as to minimize the lift entailed in engaging a bumper or other part receiving the lifting effort. The screw is then driven to feed the nut, slide, and adapter upwardly until the load has been raised the desired distance. It is of course necessary to manually maintain the upright position of the parts until the weight of the load takes effect. It will be seen that the slide 1 acts as a coupling between the bar 3 and the screw 5, holding the latter in proper axial alignment with said bar. Further the slide fully overcome the tendency of the nut to cock and bind under load, resulting in a smooth efficient operation without waste of applied manual effort. Th thread of the screw is suificiently limited in upward extent to prevent excessive upwardly shifting the slide, such as would unduly reduce the couplin connection between the thrust bar and screw. By adjusting the slide to its lower limiting position, close to the base, and by also shifting the adapter to its lowermost position on the slide, the jack may be adapted to pick up a load from a level only a few inches from the floor or ground.

When the described jack is not in use, the thrust bar may be withdrawn from the slide, largely reducing the jack length. For a maximum compactness, the screw may be either withdrawn from the slide or entered a maximum distance within the latter. The handle is readily removable from the screw and the adapter readily detached from its support 9. Adaptability of the jack to thus be reduced to a very compact form 3 not only facilitates its storage in a vehicle, but is an asset in shipping.

It will be noted that the higher a load is lifted, the more fully the screw is reinforced by the slide 1 in conjunction with the nut. This reinforcing effect makes feasible employment of a screw of considerably smaller diameter than would otherwise be necessary, a factor of importance in reducing the cost of the screw and particularly the threading cost.

What I claim is:

1. A lifting jack comprising a base, a thrust bar seated on and upstanding on the base, a load-transmitting slide movable up and down on the thrust bar, a load-engaging adapter on the slide, a screw upwardly extending from and rotatably seated on the thrust bar, a nut engaging the screw and supporting the slide, and means for rotatin the screw.

2. A lifting jack comprising a base, a thrust bar seated on and upstanding from the base, a screw rotatively seated on and upstanding from the thrust bar, a nut engaging the screw for up and down actuation by the screw, a coupling member carried by-the nut and slidably fitting said bar to maintain axial alignment of the bar 4 and screw, and a load-engaging adapter carried by said coupling member.

3. A lifting jack comprising a base, a thrust bar seated on and upstanding from the base, a load-transmitting slide movable up and down on and extending upwardly beyond the thrust bar, a load-engaging adapter on the slide, a screw upwardly extending from and rotatably seated on the thrust bar, a nut fixed within the upper portion of the slide above the thrust bar and supporting the slide, and means for rotating the screw.

CLAUDE H. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

